The invention relates to a commercial-break detection device for the detection of commercial-break information present in picture information of a television signal, having detection means arranged to receive the television signal and adapted to detect black-frame information in the picture information of the television signal, and having memory means for the storage of black-frame time information for each one of at least two units of detected black-frame information, and having analysis means for analyzing the stored black-frame time information and for determining commercial-break position information identifying the commercial-break information in the picture information.
The invention further relates to a recording and reproducing apparatus having recording means for recording film information and picture information of a television signal, which picture information includes commercial-break information, and having reproducing means for reproducing the film information and for skipping the commercial-break information during reproduction of the picture information of the recorded television signal.
Such a commercial-break detection device of the type defined in the opening paragraph and such a recording and reproducing apparatus of the type defined in the second paragraph are known from the document U.S. Pat. No. 5,987,210 are known and are formed by a video recorder. The known video recorder has recording means for recording a television signal on a magnetic tape and reproducing means for reproducing a recorded television signal. Magnetic tape transport means of the video recorder are adapted to provide transport of the magnetic tape with a normal transport speed during the recording and reproduction of the television signal and to provide transport of the magnetic tape with a winding transport speed when reproduction of a part of the recorded television signal is to be skipped.
A television signal comprises picture information, sound information and additional information, such as for example teletext information. The television signal may transmit a television film as film information, which may be interrupted by a plurality of units of commercial-break information of a plurality of commercial breaks. Each commercial break usually comprises a plurality of commercial messages.
The known video recorder includes a commercial-break detection device adapted to detect a commercial break and to mark the recording position of the commercial break on the magnetic tape by commercial-break position information. During the reproduction of the recorded television signal the recording positions of the magnetic tape, which are marked with the commercial-break position information, are skipped by transport of the magnetic tape at the winding transport speed. Thus, the commercial messages are skipped automatically without the intervention of the user of the video recorder.
The known commercial-break detection device includes detection means adapted to detect black-frame information in the picture information. Black-frame information is present in the picture information when the luminance signal of the television signal has an amplitude value below a black level threshold value during a complete field. When the detection means detect black-frame information they supply black-frame time information representative of the time relationship or position of the detected black-frame information in the television signal or, alternatively, of the recording position of the blackframe information on the magnetic tape. Black-frame time information supplied by the detection means is stored in memory means of the video recorder.
The known commercial-break detection device further includes analysis means adapted to analyze whether the time difference between adjacent units of frame picture time information corresponds to a predetermined preset time difference. Thus, it is checked whether black-frame information is followed by further black-frame information within 35 seconds or whether black-frame information is followed by the subsequent black-frame information within a preset time difference of 43 seconds to 50 seconds. These preset time differences are based on the fact that commercials usually have a length of 30 seconds, 45 seconds or 60 seconds.
The known recording and reproducing apparatus and the known commercial-break detection device are found to have the drawback that television films comparatively often contain black-frame information that can lead to an erroneous detection result, owing to which parts of the recorded television film are skipped during playback.